The present invention relates to a method for electrically coalescing emulsions especially those containing lipophilic fluid. The present invention is also directed to a method to treat fabrics wherein such an emulsion is created during the treatment process and requires electric coalescence prior to reuse of the lipophilic fluid.
Conventional laundering techniques for the cleaning and treatment of fabric articles such as garments have long involved both traditional aqueous based washing and a technique commonly referred to as xe2x80x9cdry cleaningxe2x80x9d. Traditional aqueous based washing techniques have involved immersion of the fabric articles in a solution of water and detergent or soap products followed by rinsing and drying. However, such conventional immersion cleaning techniques have proven unsatisfactory on a wide range fabric articles that require special handling and/or cleaning methods due to a fabric content, construction, etceteras, that is unsuitable for immersion in water.
Accordingly, the use of the laundering method of xe2x80x9cdry cleaningxe2x80x9d has been developed. Dry cleaning typically involves the use of non-aqueous, lipophilic fluids as the solvent or solution for cleaning. In this manner, fabrics which are incompatible with water immersion may be cleaned and treated without the potential distatrous side effects water may present.
While a broad range of non-aqueous, lipophilic fluids are available, many require the presence of low levels of water in the form of emulsions or microemulsions to maximize cleaning efficiency without sacrificing the xe2x80x9csafetyxe2x80x9d accorded fabrics via dry cleaning. In addition, it is desirable to re-cycle and/or purify these non-aqueous, lipophilic fluids to minimize the much higher operating cost associated with dry cleaning as opposed to its aqueous based cousin. However, it is desirable to separate water from the emulsion prior to some of the lipophilic purification steps. Thus, a cost-effective, efficient, and safe way to break these emulsions is desired, particularly when adjuncts such as emulsifiers are utilized.
Separation techniques for breaking petroleum/water emulsions are known. The petroleum industry has employed electric coalescence as a separation technique for emulsions and mixtures of water and petroleum in an effort to provide safe cost effective removal of water from petroleum. Such processes have been reported and exemplified in U.S. Pat. Nos. 3,207,686; 3,342,720; 3,772,180; 3,939,395; 4,056,451; 4,126,537 and 4,308,127, the disclosures of which are all herein incorporated by reference. While these references discuss the separation of the petroleum/water emulsions, they fail to teach or disclose such separation in the presence of an emusilier whose purpose is to preserve the emulsion and prevent separation.
Traditional separation techniques for dry cleaning solvent/water emulsions and/or mixtures typically involve distillation of the emulsion and/or mixture. However, distillation often involves high operating costs in the form of energy and equipment necessary to achieve the separation and, thus is undesirable in many instances.
While the references above discuss dehydrating petroleum, they do not recognize that silicone-containing compounds and polymers, which are different materials than petroleum, may also exist in emulsions with water and may also require separation. Further, while U.S. Pat. No. 5,861,089, herein incorporated by reference, recognizes that silicone-containing compounds and polymers may require separation from water, the Patent is directed to a hydrolysis or xe2x80x9cleechingxe2x80x9d process wherein water is added to the silicone-containing compounds or polymers in order to remove a particular molecule or molecules. Once the water xe2x80x9cleechesxe2x80x9d out the sought after molecule or molecules, the water is then separated from the silicone containing compounds or polymers, leaving them free or substantially free of the undesired molecule or molecules.
The process described above, however, does not require the creation of a stable or semi-stable emulsion. It only requires contacting the water with the silicone-containing compounds and/or polymers until the xe2x80x9cleechingxe2x80x9d is substantially completed. In the present invention however, a stable or semi-stable emulsion may be created either purposely through the use of the emulsifiers previously described or inadvertently during the recovery step that occurs after fabric treatment. As such, U.S. Pat. No. 5,861,089 recognizes neither the necessity nor the capability to xe2x80x9cbreakxe2x80x9d these stable or semi-stable emulsions via the use of electric coalescence.
Accordingly, the need remains for a cost effective, efficient, and safe separation method for lipophilic fluids and water, particularly when an emulsifier is present.
This need is met by the present invention wherein a process for separating an emulsion having emulsification enhancing materials present therein via the use of electric coalescence is provided. Electric coalescence provides a cost effective, efficient and safe alternative to conventional separation techniques presently employed. The present invention has two embodiments.
In a first embodiment the present invention provides a process for separating an emulsion, the process comprising exposing an emulsion comprising a continuous phase, a discontinuous phase, and an emulsifier to an electric field effecting coalescence of the discontinuous phase into droplets of a size for effective gravitation from the emulsion, where the continuous phase and the discontinuous phase have different dielectric constants and densities.
In a second embodiment the present invention provides a method for treating fabrics comprising, a fabric treatment step comprising exposing said fabrics to lipophilic fluid and water, a collection step comprising collecting at least a portion of said lipophilic fluid and said water (wherein one is the continuous phase and the other is the discontinuous phase) in a stable or semi-stable emulsion; and, a processing step comprising passing said emulsion through an electric field effecting coalescence of the discontinuous phase into droplets of a size for effective gravitation from said mixture.
These and other aspects, features and advantages will become apparent to those of ordinary skill in the art from a reading of the following detailed description and the appended claims. All percentages, ratios and proportions herein are by weight, unless otherwise specified. All temperatures are in degrees Celsius (xc2x0 C.) unless otherwise specified. All measurements are in SI units unless otherwise specified. All documents cited are in relevant part, incorporated herein by reference.